The evolution of allogeneic cultured keratinocyte treatments; clinical experiences and future possibilities

Allogeneic cultured keratinocytes do not cause acute rejection and generally "take" better on the grafted sites. They are thought to be gradually replaced by host cells and that they stimulate wound healing. Since massive allogeneic cultured keratinocytes can be made from a small number of donors, they are more cost effective than autologous ones. Especially, they can be grown faster and more efficiently if the donors are younger. Furthermore, they can be cryopreserved and used anytime for urgent cases. Lyophilized ones can even be stored at room temperature without a freezer. These characteristics are quite beneficial for both patients and clinicians alike. Since 1987, we have treated 149 patients with various ailments including deep dermal burns, tattoos, skin graft donor sites, chronic ulcers and so on with allogeneic cultured keratinocytes. Non-cryopreserved allogeneic cultured keratinocytes were used in 9 cases, cryopreserved ones in 100 cases, and lyophilized ones in 40 cases. Wound healing of the grafted sites was stimulated and they healed in a short time. There were no apparent differences in the wound healing process among these three types of allogeneic cultured keratinocytes. In all of the cases the grafted areas demonstrated a better cosmetic appearance and texture compared to conventional treatments. A lot of wound coverage materials and skin substitutes have been developed. As a base criterion these treatments should not only stimulate wound healing but also be cost effective. We think that allogeneic cultured keratinocytes grafting meets this requirement. We have used non-cryopreserved ones as the first generation of treatment, cryopreserved ones as the second generation, and then lyophilized ones as the third generation. Further improvement will be expected as we move to the fourth generation.